scripts: Fix missing line break in gdb_macros.py

pycodestyle correctly detects that there isn't
two line breaks after the end of the class here.
The test pool pep8 does not catch this. We need
to move the test pool to the newer pycodestyle
tool.

Change-Id: I5fa8b66f8c3d76e41140e79fdcd264d7b38f86c7
Signed-off-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-on: https://review.gerrithub.io/c/444445


Reviewed-by: Seth Howell <seth.howell5141@gmail.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>